An interesting experience would be to play with either a parametric EQ or a FIR based EQ until the measured frequency response is near flat, and then report how it sounds, alternatively, one could play around with EQ until it sounds flat an neutral and then measure the FR (that's more or less what LFF did with the Paradox if I'm not wrong).
I think the HD 650, the HD 800 or the LCD-3 should be quiet appropriate for these endeavors since their FR is quite regular to begin with.